Near surface electric field enhancement: Pyridinic-N rich few-layer graphene encapsulating cobalt catalysts as highly active and stable bifunctional ORR/OER catalyst for seawater batteries

Rechargeable seawater batteries (SWBs) are recently considered as a new approach in next-generation energy storage. However, the presence of chloride ions inhibits the performance and durability of the air cathode electrocatalysts. This study is the first research to report the effect of the built-in electric field on corrosion prevention via Cl- repulsion. Our DFT model successfully demonstrated the near-surface charge transfer at the interface of cobalt core and pyridinic-N graphene (Co (fcc)/N-Gr) strongly contributed to advanced catalytic activity and selectively Cl- repulsion in seawater electrolyte. Experimentally, the structure of a few layered N-doped graphene encapsulated cobalt (Co 4 mmol-N/C) showed superior catalytic activity in both alkaline (ΔE (Ej=10 − E1/2) = 0.774 V) and seawater (ΔE = 1.167 V). Furthermore, Co 4 mmol-N/C demonstrated an extremely low overpotential (0.56 V) at 0.1 mA and presented superior stability for 100 h in a rechargeable SWB. [Display omitted] •First research to report the effect of built-in electric field on Cl- repulsion.•Co(fcc)/N-Gr interface contributes to superior catalytic activity and Cl- repulsion.•Co 4 mmol-N/C demonstrates a low overpotential (0.56 V) in rechargeable SWBs.•The overvoltage of Co 4 mmol-N/C merely increases 10% after 100-hour cycles.•Surface pyridinic-N in N/C shell was converted to pyridonic-N after durability test.